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| United States Patent |
5,780,769
|
|
Russell
, et al.
|
July 14, 1998
|
Thermal stabilization of N,N-dinitramide salts
Abstract
The thermal stability of an N,N-dinitramide salt of the formula M.sup.+
›N(NO.sub.2).sub.2 !.sup.- where M.sup.+ is a nitrogen-containing cation,
is improved by mixing with the N,N-dinitramide salt a compound of the
formula
##STR1##
where R, R' and R" are the same or different and are aryl or alkyl. A new
composition of matter is formed by mixing the N,N-dinitramide salt and the
prophosphatrane compound.
| Inventors:
|
Russell; Thomas P. (Manassas Park, VA);
Mishra; Indu B. (Columbia, MD)
|
| Assignee:
|
The United States of America as represented by the Secretary of the Navy (Washington, DC)
|
| Appl. No.:
|
708001 |
| Filed:
|
August 26, 1996 |
| Current U.S. Class: |
149/45; 149/92; 149/109.6; 423/385; 423/387; 564/107; 564/109 |
| Intern'l Class: |
C06B 031/00; C06B 025/34; C01B 021/20; C07C 111/00 |
| Field of Search: |
149/45,92,109.6
423/385,387
564/107,109
|
References Cited
U.S. Patent Documents
| 5051533 | Sep., 1991 | Verkade | 564/13.
|
| 5198204 | Mar., 1993 | Bottaro et al. | 423/385.
|
| 5254324 | Oct., 1993 | Bottaro et al. | 423/263.
|
| 5292387 | Mar., 1994 | Highsmith et al. | 149/19.
|
| 5316749 | May., 1994 | Schmitt et al. | 423/385.
|
| 5415852 | May., 1995 | Schmitt et al. | 423/385.
|
| 5498303 | Mar., 1996 | Hinshaw et al. | 149/19.
|
| 5507893 | Apr., 1996 | Mullay et al. | 149/92.
|
| Foreign Patent Documents |
| WO 91/19670 | Dec., 1991 | WO | .
|
| WO 91/19669 | Dec., 1991 | WO | .
|
| WO 94/24073 | Oct., 1994 | WO | .
|
Other References
Lensink C, Xi K, Daniels L M and Verkade J G, The Unusually Robust P-H Bond
n the Novel Cation HP(NMeCH.sub.2 CH.sub.2).sub.3 N.sup.+ J. Am. Chem Soc.
1989, 111, 3478-3479.
|
Primary Examiner: Miller; Edward A.
Attorney, Agent or Firm: McDonnell; Thomas E., Webb; Ralph T.
Claims
What is claimed is:
1. A composition comprising
an N,N-dinitramide salt of the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.-
where M.sup.+ is a nitrogen-containing cation, and
a prophosphatrane compound of the formula
##STR6##
where R, R' and R" are the same or different and are aryl or alkyl.
2. The composition of claim 1, wherein M.sup.+ is selected from the group
consisting of an ammonium ion, a monoalkylammonium ion, a dialkyl ammonium
ion, a trialkyl ammonium ion, and a tetraalkyl ammonium ion.
3. The composition of claim 1 wherein M.sup.+ is an ammonium ion.
4. The composition of claim 1 wherein R, R' and R" are selected so that
said prophosphatrane compound is a solid at temperatures up to and
including 70.degree. C.
5. The composition of claim 1, wherein R, R' and R" are selected from the
group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, cyclopentyl,
cyclohexyl, cylcopentadienyl, phenyl, benzyl, benzoyl or toluyl.
6. The composition of claim 1 wherein R, R', and R" are methyl.
7. The composition of claim 1 wherein the amount of said prophosphatrane
compound is from about 0.003 to about 1% by mole of the amount of said
N,N-dinitramide salt.
8. The composition of claim 1 wherein the amount of said prophosphatrane
compound is from about 0.01 to about 0.5% by mole of the amount of said
N,N-dinitramide salt.
9. A composition comprising ammonium dinitramide and a prophosphatrane
compound of the formula P›MeNCH.sub.2 CH.sub.2 CH.sub.2).sub.3 N!.
10. A composition of matter formed by the process of combining an
N,N-dinitramide salt of the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.+
where M.sup.- is a nitrogen-containing cation with a prophosphatrane
compound of the formula
##STR7##
where R, R' and R" are the same or different and are aryl or alkyl.
11. The composition of claim 10, wherein M.sup.+ is selected from the group
consisting of an ammonium ion, a monoalkylammonium ion, a dialkyl ammonium
ion, a trialkyl ammonium ion, and a tetraalkyl ammonium ion.
12. The composition of claim 10 wherein M.sup.+ is ammonium ion.
13. The composition of claim 10 wherein R, R' and R" are selected so that
said prophosphatrane compound is a solid at temperatures up to and
including 70.degree. C.
14. The composition of claim 10, wherein R, R' and R" are selected from the
group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, cyclopentyl,
cyclohexyl, cylcopentadienyl, phenyl, benzyl, benzoyl or toluyl.
15. The composition of claim 10 wherein R, R', and R" are methyl.
16. The composition of claim 10 wherein the amount of said prophosphatrane
compound is from about 0.003 to about 1% by mole of the amount of said
N,N-dinitramide salt.
17. The composition of claim 10 wherein the amount of said prophosphatrane
compound is from about 0.01 to about 0.5% by mole of the amount of said
N,N-dinitramide salt.
18. A composition of matter formed by the process of combining ammonium
dinitramide with a prophosphatrane compound of the formula P›MeNCH.sub.2
CH.sub.2).sub.3 N! wherein the amount of said prophosphatrane compound is
from about 0.003 to about 1% by mole of the amount of the ammonium
dinitramide.
19. A method of improving the thermal stability of an N,N-dinitramide salt
of the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.- where M.sup.+ is a
nitrogen-containing cation comprising the step of adding to said
N,N-dinitramide salt a prophosphatrane compound of the formula
##STR8##
where R, R' and R" are the same or different and are aryl or alkyl.
20. The method of claim 19, wherein M.sup.+ is selected from the group
consisting of an ammonium ion, a monoalkylammonium ion, a dialkyl ammonium
ion, a trialkyl ammonium ion, and a tetraalkyl ammonium ion.
21. The method of claim 19 wherein M.sup.+ is an ammonium ion.
22. The method of claim 19 wherein R, R' and R" are selected so that said
prophosphatrane compound is a solid at temperatures up to and including
70.degree. C.
23. The method of claim 19, wherein R, R' and R" are selected from the
group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, cyclopentyl,
cyclohexyl, cylcopentadienyl, phenyl, benzyl, benzoyl or toluyl.
24. The method of claim 19 wherein R, R', and R" are methyl.
25. The method of claim 19 wherein the amount of said prophosphatrane
compound is from about 0.003 to about 1% by mole of the amount of said
N,N-dinitramide salt.
26. The method of claim 19 wherein the amount of said prophosphatrane
compound is from about 0.01 to about 0.5% by mole of the amount of
N,N-dinitramide salt.
27. A method of improving the thermal stability of ammonium dinitramide
comprising the step of adding to ammonium dinitramide a prophosphatrane
compound of the formula P›MeNCH.sub.2 CH.sub.2).sub.3 N!.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to the stabilization of energetic compounds
and, in particular, to methods of improving the thermal stability of
ammonium dinitramide and other N,N-dinitramide salts by adding a
prophosphatrane compound as a stabilizer.
2. Description of the Related Art
Ammonium dinitramide is an energetic compound recently developed for use as
an explosive and as an oxidizer in solid rocket propellant compositions.
The compound has an advantage over compounds such as ammonium perchlorate
and potassium perchlorate that are currently used as oxidizers in solid
propellants in that it does not contain chlorine. Chlorine-containing
compound produce an undesirable smoke trail or signature and may be
hazardous to the environment.
A disadvantage of ammonium dinitramide is that the compound begins to
decompose when exposed to UV radiation between 200 and 330 nm or to
temperatures above 55.degree. C. When the compound decomposes, it loses
its stored energy and produces a gaseous decomposition product, nitrous
oxide (N.sub.2 O). This quality limits the usefulness of ammonium
dinitramide in a propellant, since it can be expected that a propellant
will be exposed to UV radiation and temperatures as high as 70.degree. C.
(158.degree. F.) during the ordinary course of development, transportation
and storage. The production of a gaseous decomposition product during
storage of a solid propellant is hazardous.
Other N,N-dinitramide salts of the formula M.sup.+ ›N(NO.sub.2).sub.2
!.sup.+ where M.sup.+ is a nitrogen-containing cation have similar
advantages and disadvantages.
Attempts have been made to stabilize ammonium dinitramide using potassium
dinitramide, potassium fluoride (which can be used to phase stabilize
ammonium nitrate (U.S. Pat. No. 4,552,736)), phenylphosphine pentamer,
phenylphosphine hexamer and phenylphosphine polymers.
U.S. Pat. No. 5,498,303 to Hinshaw, Wardle and Highsmith describes a
propellant formulation that includes ammonium dinitramide and
curatives/stabilizers (Col. 4, lines 9-14). The curatives/stabilizers
mentioned are 0.4% MNA (N-methyl-p-nitroaniline), 3.11% Desmodur.RTM.
N-100, a polyisocyanate curative, 0.5% acid scavenger
(N,N,N',N'-tetramethyl-1,8-naphthalenediamine (a strong base) and 0.005%
TPB (triphenyl bismuth).
U.S. Pat. No. 5,254,324 to Bottaro, Schmitt, Penwell and Ross, U.S. Pat.
No. 5,198,204 to Bottaro, Schmitt, Penwell and Ross, and U.S. Pat. No.
5,415,852 to Schmitt, Bottaro, Penwell and Bomberger disclose dinitramide
salt compositions of the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.- where
M.sup.+ is a metal cation or a nitrogen containing cation.
U.S. Pat. No. 5,051,533 describes prophosphatrane compounds (P(RNCH.sub.2
CH.sub.2).sub.3 N) and discloses that these compounds are very strong
Lewis bases, stronger than 1,8-(bisdimethylamino)-naphthalene (another
name for N,N,N',N'-tetramethyl-1,8-naphthalenediamine).
SUMMARY OF THE INVENTION
An object of the invention is to improve the thermal stability of ammonium
dinitramide or other N,N-dinitramide salts in the temperature range that
may be encountered in the development, transportation and storage of the
compounds or of propellant formulations containing the compounds. In
particular, it is an object of the invention to improve the thermal
stability of ammonium dinitramide and other N,N-dinitramide salts for
temperatures above 55.degree. C. A further object of the invention is that
any additive used to improve the thermal stability of ammonium dinitramide
and other N,N-dinitramide salts not contain halogenated or metallic
compounds. Halogenated and metallic compounds create a signature when used
in a rocket propellant. Metallic compounds tend to have a high molecular
mass, which lowers the specific impulse of exhaust gases. A further object
of the invention is that any additive used to improve the thermal
stability of ammonium dinitramide and other N,N-dinitramide salts be
effective in small quantities, preferably in the range of 0.003-1.00% by
mole and most preferably in the range of 0.01-0.5% by mole.
These and other objects are achieved by adding to a N,N-dinitramide salt of
the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.-, where M.sup.+ is a
nitrogen-containing cation, a prophosphatrane compound of the formula
##STR2##
where R, R' and R" are the same or different and are aryl or alkyl. It has
been found that a small amount (as little as 0.003% by mole) of a
prophosphatrane compound according to the above formula, when added to
ammonium dinitramide, greatly inhibits the thermal degradation of the
ammonium dinitramide. In addition, the compound absorbs UV radiation in
the range of 200-330 nm and thus may serve to protect ammonium dinitramide
from UV-caused degradation. The invention further relates to a composition
comprising a N,N-dinitramide salt of the formula M.sup.+
›N(NO.sub.2).sub.2 !.sup.-, where M.sup.+ is a nitrogen-containing
cation, and a prophosphatrane compound as described above and to a
composition of matter created by combining the N,N-dinitramide salt and a
prophosphatrane compound.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows infrared spectra of absorbance versus wavenumber in the range
of 2290-2160 cm.sup.-1 (the range for detecting N.sub.2 O) for a mixture
of ammonium dinitramide and P(MeNCH.sub.2 CH.sub.2).sub.3 N that was
heated at 90.degree. C. for 20 hours. The infrared spectra were collected
every two hours, and the spectra are shown as superimposed on a single
graph.
FIG. 2 shows superimposed infrared spectra of absorbance versus wavenumber
in the range of 3400-2800 cm.sup.-1 (the range for detecting ammonium
nitrate) for a mixture of ammonium dinitramide and P(MeNCH.sub.2
CH.sub.2).sub.3 N that was heated at 90.degree. C. for 65 hours. The
infrared spectra were collected at 24, 40 and 65 hours.
FIGS. 3-5 show superimposed comparative infrared spectra of absorbance
versus wavenumber in the range of 3400-2800 cm.sup.-1 (the range for
detecting ammonium nitrate) for ammonium dinitramide (ADN), a mixture of
ammonium dinitramide and P(MeNCH.sub.2 CH.sub.2).sub.3 N (ADN/VC), a
mixture of ammonium dinitramide and potassium fluoride (ADN/KF) and a
mixture of ammonium dinitramide and potassium dinitramide (ADN/KDN). All
samples were heated at 90.degree. C. for 24 hours. Spectra were collected
at 10 hours (FIG. 3), 18 hours (FIG. 4) and 24 hours (FIG. 5).
FIGS. 6-8 show superimposed comparative infrared spectra of absorbance
versus wavenumber in the range of 2290-2160 cm.sup.-1 (the range for
detecting N.sub.2 O) for ammonium dinitramide (ADN), a mixture of ammonium
dinitramide and P(MeNCH,CH.sub.2).sub.3 N (ADN/VC), a mixture of ammonium
dinitramide and potassium fluoride (ADN/KF) and a mixture of ammonium
dinitramide and potassium dinitramide (ADN/KDN). All samples were heated
at 90.degree. C. for 24 hours. Spectra were collected at 10 hours (FIG.
6), 18 hours (FIG. 7) and 24 hours (FIG. 8).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Ammonium dinitramide is a solid compound that can be prepared by any method
known in the art, including the methods disclosed in U.S. Pat. No.
5,198,204 to Bottaro et al, U.S. Pat. No. 5,316,749 to Schmitt et al, U.S.
Pat. No. 5,254,324 to Bottaro et al and U.S. Pat. No. 5,415,852 to Schmitt
et al, each patent being incorporated herein in its entirety and for all
purposes. The compound, sometimes referred to as ADN or ammonium
dinitramide salt, is useful as an explosive and as an oxidizer in solid
propellant formulations. Examples of propellant formulations containing
ammonium dinitramide are found in U.S. Pat. No. 5,498,303 to Hinshaw,
incorporated herein by reference in its entirety and for all purposes.
Other N,N-dinitramide salts of the formula M.sup.+ ›N(NO.sub.2).sub.2
!.sup.-, where M.sup.+ is a nitrogen-containing cation, are described in
the above-cited patents. The method of the present invention for improving
thermal stability of ammonium dinitramide applies to these compounds as
well. Preferably, the compounds that are stabilized according to the
method of the present invention include N,N-dinitramide salts of the
formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.- where M.sup.+ is selected from
the group consisting of an ammonium ion, a monoalkylammonium ion, a
dialkyl ammonium ion, a trialkyl ammonium ion, and a tetraalkyl ammonium
ion.
According to the present invention, the thermal stability of a
N,N-dinitramide salt of the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.-,
where M.sup.+ is a nitrogen-containing cation, is improved by adding to
the N,N-dinitramide salt a prophosphatrane compound of the formula
##STR3##
where R, R' and R" are the same or different and are aryl or alkyl.
The identity of the R, R' and R" groups on the prophosphatrane compound
affects whether the prophosphatrane compound is a liquid or a solid. For
use as a stabilizer in a solid propellant, it is preferred that the
prophosphatrane compound be a solid at temperatures up to and including
70.degree. C. Liquid additives or compounds that melt at or below
70.degree. C. may migrate to the surface of the propellant during storage.
Prophosphatrane compounds tend to be solid when R, R' and R" are methyl
groups, short alkyl chains or small aryl groups. The compounds tend to be
liquids when R, R' and R" are groups with more than about 6-8 carbon
atoms. Preferably, in the present invention, R, R' and R" are selected
from the group consisting of methyl, ethyl, propyl, isopropyl, butyl,
isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl,
cyclopentyl, cyclohexyl, cyclopentodienyl, phenyl, benzyl, or benzoyl or
toluyl. Most preferably, R, R' and R" are methyl. Prophosphatranes used in
the present invention are also called proazaphosphatranes, phosphatranes,
Verkade's compounds or VC's. When R, R' and R" are alike, the class of
compounds may also be referred to as P›(RNCH.sub.2 CH.sub.2).sub.3 N!.
When R, R' and R" are all methyl groups, the compound may also be referred
to by its chemical formula, P›(MeNCH.sub.2 CH.sub.2).sub.3 N! or by its
chemical name, 2,8,9-trimethyl-1-phospha-2,5,8,9,-tetrazabicyclo›3,3,3!
undecane. Prophosphatrane compounds and a method for making them are
disclosed in U.S. Pat. No. 5,051,533 to Verkade, incorporated herein by
reference in its entirety and for all purposes.
The thermal stablility of N,N-dinitramide salts is improved when only a
trace amount of a prophosphatrane compound is added. Preferably, the
amount of the prophosphatrane compound is at least 0.003% by molar
percent, based on the amount of the N,N-dinitramide salt. Although there
is no upper limit to the amount of the prophosphatrane compound that can
be used, for practical use in a solid propellant it is preferred that the
amount of the prophosphatrane compound not exceed 1.00% by molar percent,
based on the amount of the N,N-dinitramide salt. Most preferably the
amount of the prophosphatrane compound is 0.01-0.5 by molar percent, based
on the amount of N,N-dinitramide salt. Because the prophosphatranes absorb
UV light in the range of 200-330 nm, the addition of a prophosphatrane
compound will also help to protect N,N-dinitramide salts from UV
degradation.
Both the N,N-dinitramide salts and the preferred prophophatrane compounds
as defined above are solid compounds that can be made into powders. In
practicing the method of this invention, the mixing of the N,N-dinitramide
salt and the prophosphatrane compound is accomplished by any mechanical
means at any convenient time prior to the long-term storage of the
N,N-dinitramide salt or the storage of an explosive or propellant
composition containing the N,N-dinitramide salt.
A further aspect of the present invention is a composition comprising a
N,N-dinitramide salt of the formula M.sup.+ ›N(NO.sub.2).sub.2 !.sup.-,
where M.sup.+ is a nitrogen-containing cation, and a prophosphatrane
compound of the formula
##STR4##
where R, R' and R" are the same or different and are aryl or alkyl.
Preferably, R, R' and R" are selected from the group consisting of methyl,
ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl,
neopentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl,
cyclopentadienyl, phenyl, benzyl, benzoyl or toluyl. Most preferably, R,
R' and R" are methyl. The prophosphatrane compound is preferably present
in the amount of about 0.003 to about 1% by mole and most preferably in
the amount of 0.01-0.5% by mole of the amount of the N,N-dinitramide salt.
Although the inventors do not intend to be bound by any particular theory
of the invention, they theorize that the prophosphatrane compound acts as
a strong base to remove ammonia from the ammonium dinitramide, forming
dinitramidic acid. Free NH.sub.3 gas can be detected when ammonium
dinitramide and a prophosphatrane compound are mixed. The prophosphatrane
compound then deprotonates the dinitramidic acid, thereby forming
{HP›(RNCH.sub.2 CH.sub.2).sub.3 !N}.sup.+ and the dinitramide anion,
›N(NO.sub.2).sub.2 !.sup.-. The dinitramide anion is then protected from
further degradation. The prophosphatrane compound is believed to act
similarly with other N,N-dinitramide salts. Accordingly, therefore, the
invention includes a new composition of matter formed by the process of
combining a N,N-dinitramide salt of the formula M.sup.+ ›N(NO.sub.2).sub.2
!.sup.-, where M.sup.+ is a nitrogen-containing cation, with a
prophosphatrane compound of the formula
##STR5##
where R, R' and R" are the same or different and are aryl or alkyl.
Preferably, R, R' and R" are selected from the group consisting of methyl,
ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl,
neopentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl,
cyclopentadienyl, phenyl, benzyl, benzoyl or toluyl. Most preferably, R,
R' and R" are methyl. The prophosphatrane compound is preferably added in
the amount of about 0.003 to about 1% by mole and most preferably in the
amount of about 0.01 to about 0.5% by mole of the amount of the
N,N-dinitramide salt. It is expected that such a composition of matter
would include {HP›(RNCH.sub.2 CH.sub.2).sub.3 !N}.sup.+ and the
dinitramide anion, ›N(NO.sub.2).sub.2 !.sup.-, as well as any unreacted
N,N-dinitramide salt or prophosphatrane compound.
In the development, storage and transportation of solid propellants
containing ammonium dinitramide or other N,N-dinitramide salts, it is
possible for dinitramide salt to be exposed to temperatures in the range
of 55.degree. C. to 70.degree. C. for up to 12 hours at a time (during
temperature cycles of day (hot) and night (cold)). Therefore, an objective
of the present invention is to improve the thermal stability of
N,N-dinitramide salts to the extent that they do not decompose when heated
at 70.degree. C. for 12 hours. The thermal stability of any given ammonium
dinitramide composition can be readily determined by heating the
composition to 90.degree. C. and measuring the production of the
decomposition products N.sub.2 O and ammonium nitrate. Assuming that there
is an Arrhenius relationship to the decomposition reaction such that the
rate of decomposition doubles for every 10.degree. C. in temperature, the
rate of decomposition in the range of 55.degree. C. to 70.degree. C. for
12 hours can be estimated by determining rate of decomposition at
90.degree. C. for 3 hours or less. Other N,N-dinitramide salt compositions
can be readily tested in a similar fashion.
The ability of a given prophosphatrane-containing composition to protect
ammonium dinitramide against degradation caused by exposure to UV light
can also be readily measured by exposing a sample to UV light and
measuring the production of the decomposition products N.sub.2 O and
ammonium nitrate.
Having described the invention, the following examples are given to
illustrate specific applications of the invention, including the best mode
now known to perform the invention. These specific examples are not
intended to limit the scope of the invention described in this
application.
EXAMPLE 1
Preparation and testing of a mixture of ammonium dinitramide and
P›(MeNCH.sub.2 CH.sub.2).sub.3 N!
To prepare a mixture of ammonium dinitramide and P›(MeNCH.sub.2
CH.sub.2).sub.3 N!, 100 mg of ammonium dinitramide (fwt 124,
8.065.times.10.sup.-4 moles) and 1.00 mg of P›(MeNCH.sub.2 CH.sub.2).sub.3
N! (fwt 216, 4.63.times.10.sup.-6 moles) were thoroughly mixed in a mortar
and pestle. The early evolution of NH.sub.3 was noticed and increased with
time. The mixture was enclosed in an infrared cell and heated to
90.degree. C. The cell had KBr windows and was evacuable and
pressurizable. The infrared spectra were collected every two hours. The
superimposed infrared spectra of absorbance versus wavenumber in the range
of 2290-2160 cm.sup.-1 (the range for detecting N.sub.2 O) are shown in
FIG. 1. The spectra of FIG. 1 show that only a trace of N.sub.2 O was
detected for several hours and that the amount of N.sub.2 O increased
slowly thereafter.
The superimposed infrared spectra of absorbance versus wavenumber in the
range of 3400-2800 cm.sup.-1 (the range for detecting ammonium nitrate)
for a mixture of ammonium dinitramide and P(MeNCH.sub.2 CH.sub.2).sub.3 N
that was heated at 90.degree. C. for 65 hours is shown in FIG. 2. The
infrared spectra were collected at 24, 40 and 65 hours. The spectra of
FIG. 2 show that there was no ammonium nitrate detected during the 65 hour
period.
EXAMPLE 2 (COMPARATIVE EXAMPLE)
To 100 mg of ammonium dinitramide, 2.00 mg of phenylphosphine hexamer (fwt.
648, 3.086.times.10.sup.-6 moles was added and mixed thoroughly as in
example 1. The mixture was then heated in an infrared cell with KBr
windows and its IR spectra was collected. There was an instantaneous but
slow evolution of both N.sub.2 O and ammonium nitrate.
EXAMPLE 3 (COMPARATIVE EXAMPLE)
Mixtures were prepared of 100 mg ammonium dinitramide-2.00 mg potassium
dinitramide and 100 mg ammonium dinitramide-2.00 mg potassium fluoride in
the same manner as example 1. The samples were heated at 90.degree. C. in
infrared cells and IR spectra were collected at 10, 18 and 24 hours.
Spectra were also collected for a mixture of 100 mg ammonium
dinitramide-2.00 mg P›(MeNCH.sub.2 CH.sub.2).sub.3 N! and for ammonium
dinitramide without any additive.
FIGS. 3-5 show superimposed comparative infrared spectra of absorbance
versus wavenumber in the range of 3400-2800 cm.sup.-1 (the range for
detecting ammonium nitrate) for ammonium dinitramide (ADN), the mixture of
ammonium dinitramide and P(MeNCH.sub.2 CH.sub.2).sub.3 N (ADN/VC), the
mixture of ammonium dinitramide and potassium fluoride (ADN/KF) and the
mixture of ammonium dinitramide and potassium dinitramide (ADN/KDN). The
spectra show that ammonium nitrate was not detected in the mixture of
ammonium dinitramide and P(MeNCH.sub.2 CH.sub.2).sub.3 N but was detected
in the other mixtures.
FIGS. 6-8 show superimposed comparative infrared spectra of absorbance
versus wavenumber in the range of 2290-2160 cm.sup.-1 (the range for
detecting N.sub.2 O) for ammonium dinitramide (ADN), the mixture of
ammonium dinitramide and P(MeNCH.sub.2 CH.sub.2).sub.3 N (ADN/VC), the
mixture of ammonium dinitramide and potassium fluoride (ADN/KF) and the
mixture of ammonium dinitramide and potassium dinitramide (ADN/KDN). In
all the figures, the least amount of N.sub.2 O is detected in the sample
containing the mixture of ammonium dinitramide and P(MeNCH.sub.2
CH.sub.2).sub.3 N.
Obviously, many modifications and variations of the present invention are
possible in light of the above teachings. It is therefore to be understood
that, within the scope of the appended claims, the invention may be
practiced otherwise than as specifically described.
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